Here is the full list of all 25 Seduce Me the Otome achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Witness Simon's Transformation with Diana and someone special...
Give Damien his Humanity.
Share some Cake with Matthew.
Preview the start of Seduce Me 2: The Demon War!
Accept Sam for the Man he is.
Turn down sex, but keep your true love.
Kiss Erik under the Moonlight.
Get Proposed to by James.
Obtain True Power.
Prove Your Love to Suzu.
Get Shot in the head by Malix.
Obtain True Freedom.
Start your Adventure with Diana.
Go To Paris with Naomi.
Be Eaten Alive by Diana's Pit Beast.
Rename the Main Character.
Get Proposed to by Andrew.
Be Baptized by Angels.
Fight Malix Yourself.
Dodge Malix in time.
Unlock the Second Set of Bloopers!
Find Harold Anderson's Magic Books.
Unlock the First Set of Bloopers!
Impress the House Party Guests.
Prologue Completed!